When you are asked to solve an equation, you need to isolate the variable which is t in this case. To isolate t, you would divide both sides by -5 and be left with t=-6 which is the final answer.
I hope this helps.
♥ Solve:
(Arjun) 40*30=1200
(Dalia) 55*30=1650
Now subtract
1650-1200=450.
That means that Dalia will type 450 minutes more.
Final answer: 450